Design of a TiO2 nanosheet/nanoparticle gradient film photoanode and its improved performance for dye-sensitized solar cells

Full near-ultraviolet response photoelectrochemical ultraviolet detector based on TiO2nanocrystalline coated stainless steel mesh photoanode

In order to solve the 'ultraviolet (UV) filtering problem' caused by traditional sandwich-type structure in photoelectrochemical (PEC) UV detector, we design a special electrode based on stainless steel mesh, which integrates the light absorption layer and the electron collection electrode in a simple way. In combination with an UV-transparent quartz substrate, UV light can directly reach the active material. The improved detector shows good visible-blind, self-powered, and linear response characteristics. The serious recombination caused by metal electrode is suppressed by depositing a barrier layer. The optimized device exhibits a high photoresponse of 0.103 A W^-1at 296 nm, a short recovery time of 250 ms, and very sensitive switching ability. Furthermore, the response range of the detector is expanded from 300 to 400 nm to the full near-UV region. Our work provides an efficient strategy to solve the key problem of the PEC UV detector.

Interface-Assisted Synthesis of the Mn3-xFexO4 Gradient Film with Multifunctional Properties

Anisotropic gradient materials are considered as promising and novel in that they have numerous functional properties and are able to transform into hierarchical microstructures. We report a facile method of gradient inorganic thin film synthesis through diffusion-controlled deposition at the gas-solution interface. To investigate the reaction of interfacial phase boundary controllable hydrolysis by gaseous ammonium, an aqueous solution of FeCl₃ and MnCl₂ was chosen, as the precipitation pH values for the hydroxides of these metals differ gradually. As a result of synthesis using the gas-solution interface technique (GSIT), a thin film is formed on the surface of the solution that consists of Mn²⁺(Fe,Mn)₂³⁺O₄ nanoparticles with hausmannite crystal structure. The ratio between iron and manganese in the film can be adjusted over a wide range by varying the synthetic procedure. Specific conditions are determined that allow the formation of a Mn-Fe mixed oxide film with a gradient of composition, morphology, and properties, as well as its further transformation into microscrolls with a diameter of 10-20 μm and a length of up to 300 μm, showing weak superparamagnetic properties. The technique reported provides a new interfacial route for the development of functional gradient materials with tubular morphology.

Synergic effect of graphene and core-shells structured Au NR@SiO2@TiO2 in dye-sensitized solar cells

Graphene and Au nanorods (AuNRs) coated with SiO₂@TiO₂ double shells (AuNR@SiO₂@TiO₂) were incorporated to form novel composite photoanodes in dye sensitized solar cells (DSSCs). The performances of the photoanodes and DSSCs are studied systematically. The short circuit current density (J _sc) and power conversion efficiency (PCE) of these composited DSSCs were greatly enhanced and the influences of the graphene, AuNRs and the SiO₂@TiO₂ double shells were revealed. The optimal properties with the maximal J _sc of 16.26 mA cm^-2 and PCE of 8.08% are obtained in the DSSC co-doped with graphene and AuNR@SiO₂@TiO₂, significantly higher than those of the conventional DSSC with pure TiO₂ photoanode by 37.7% and 32.9%, respectively. These significant enhancements in J _sc and PCE are attributed to the synergistic effect of graphene, the local surface plasma resonance of AuNRs, as well as the outer SiO₂@TiO₂ double shells, which result in the increased specific surface area and dye adsorption, the increased light absorption, the decreased charge transfer resistance R ₂ and electron recombination and thus the increased J _sc and PCE of the DSSCs.

Combined photoanodes of TiO2 nanoparticles and {001}-faceted TiO2 nanosheets for quantum dot-sensitized solar cells

A key point for constructing quantum dot-sensitized solar cells (QDSSCs) with high efficiency is to improve the utilization of sunlight.

Nanoarchitectures in dye-sensitized solar cells: metal oxides, oxide perovskites and carbon-based materials

Dye-sensitized solar cells (DSSCs) have aroused great interest and been regarded as a potential renewable energy resource among the third-generation solar cell technologies to fulfill the 21^st century global energy demand. DSSCs have notable advantages such as low cost, easy fabrication process and being eco-friendly in nature. The progress of DSSCs over the last 20 years has been nearly constant due to some limitations, like poor long-term stability, narrow absorption spectrum, charge carrier transportation and collection losses and poor charge transfer mechanism for regeneration of dye molecules. The main challenge for the scientific community is to improve the performance of DSSCs by using different approaches, like finding new electrode materials with suitable nanoarchitectures, dyes in composition with promising semiconductors and metal quantum dot fluorescent dyes, and cost-effective hole transporting materials (HTMs). This review focuses on DSSC photo-physics, which includes charge separation, effective transportation, collection and recombination processes. Different nanostructured materials, including metal oxides, oxide perovskites and carbon-based composites, have been studied for photoanodes, and counter electrodes, which are crucial to achieve DSSC devices with higher efficiency and better stability.

Growth of hierarchical TiO2 flower-like microspheres/oriented nanosheet arrays on a titanium mesh for flexible dye-sensitized solar cells

A triple-layer TiO₂ (TiO₂-TL) structure was synthesized with an over-layer composed of TiO₂ flower-like microspheres (MSs), a middle layer of nanosheet arrays (NSAs) and an under-layer of compact film (CF) on a titanium (Ti) mesh substrate using a one-step hydrothermal route and used to make a series of flexible dye-sensitized solar cells (DSSCs).

Scattering and plasmonic synergetic enhancement of the performance of dye-sensitized solar cells by double-shell SiO2@Au@TiO2 microspheres

The Au nanoparticle sandwich double spheric-shells of SiO₂@Au@TiO₂ (SAT) microspheres are synthesized. The significant influence of the SAT microspheres on the properties of dye-sensitized solar cells (DSSCs) is investigated. Studies indicate that the introduction of SAT markedly enhanced the light scattering and capture ability of DSSCs and thus photogenerated electrons. DSSCs doped with 2.25 wt% SAT exhibit a maximum short circuit current density of 17.0 mA cm^-2 and photoelectric conversion efficiency of 7.14%, which are remarkably higher than those of conventional DSSCs at 15.7% and 21.2%, respectively. The marked enhancement in the performance of the optimal DSSCs can be attributed to the synergetic complementary effect of the enhanced light scattering of the microspheres and to the localized surface plasmon resonance of the Au nanoparticles in the SAT, and is a novel promising way of enhancing the performance of DSSCs.

RGO/TiO2 nanosheets immobilized on magnetically actuated artificial cilia film: a new mode for efficient photocatalytic reaction

Exploring a proper mode for practical reaction and efficient recycle has been an extensively studied subject in the photocatalysis field.

Bilayered photoanode consisting of zinc oxide hollow spheres and urchin-like titanium dioxide microspheres enables fast electron transport and efficient light-harvesting for improved-performance dye-sensitized solar cells

Derived from ZnO hollow spheres (ZHSs) as the underlayer and urchin-like TiO₂ spheres (UTSs) as the light scattering overlayer, a new bilayered photoanode (ZHS + UTS) is fabricated for use in dye-sensitized solar cells (DSSCs).

New insight on facet-dependent physicochemical properties of anatase TiO2 nanostructures for efficient photocatalysis

Crystal growth mechanisms and physicochemical properties associated with the photocatalytic activities have been systematically investigated.

Anatase TiO2 nanosheets with exposed highly reactive (001) facets as an efficient photoanode for quantum dot-sensitized solar cells

Two-dimensional (2D) anatase TiO₂ nanosheets (TiO₂-NSs) with exposed (001) crystal planes were obtained via a simple one-pot hydrothermal route, and a high efficient CdSe quantum dots solar cell was obtained based on the TiO₂ nanosheets photoanode.

Facile synthesis of D–π–A structured dyes and their applications towards the cost effective fabrication of solar cells as well as sensing of hazardous Hg(ii)

Synthesis of two D–π–A dyes with a multidisciplinary application approach explained on the basis of electron sharing effects.

Orientation-Controllable ZnO Nanorod Array Using Imprinting Method for Maximum Light Utilization in Dye-Sensitized Solar Cells

We present a holey titanium dioxide (TiO2) film combined with a periodically aligned ZnO nanorod layer (ZNL) for maximum light utilization in dye-sensitized solar cells (DSCs). Both the holey TiO2 film and the ZNL were simultaneously fabricated by imprint technique with a mold having vertically aligned ZnO nanorod (NR) array, which was transferred to the TiO2 film after imprinting. The orientation of the transferred ZNL such as laid, tilted, and standing ZnO NRs was dependent on the pitch and height of the ZnO NRs of the mold. The photoanode composed of the holey TiO2 film with the ZNL synergistically utilized the sunlight due to enhanced light scattering and absorption. The best power conversion efficiency of 8.5 % was achieved from the DSC with the standing ZNL, which represented a 33 % improvement compared to the reference cell with a planar TiO2.

Control of Nanostructures and Interfaces of Metal Oxide Semiconductors for Quantum-Dots-Sensitized Solar Cells

Nanostructured metal oxide semiconductors (MOS), such as TiO2 and ZnO, have been regarded as an attractive material for the quantum dots sensitized solar cells (QDSCs), owing to their large specific surface area for loading a large amount of quantum dots (QDs) and strong scattering effect for capturing a sufficient fraction of photons. However, the large surface area of such nanostructures also provides easy pathways for charge recombination, and surface defects and connections between adjacent nanoparticles may retard effective charge injection and charge transport, leading to a loss of power conversion efficiency. Introduction of the surface modification for MOS or QDs has been thought an effective approach to improve the performance of QDSC. In this paper, the recent advances in the control of nanostructures and interfaces in QDSCs and prospects for the further development with higher power conversion efficiency (PCE) have been discussed.

A facile solution-based approach to a photocatalytic active branched one-dimensional TiO2 array

Branched one-dimensional TiO₂ array with enhanced photocatalytic activity was fabricated via a facile solution-based strategy.

Rapid construction of TiO2 aggregates using microwave assisted synthesis and its application for dye-sensitized solar cells

Hierarchical TiO₂ nanocrystallite aggregates are obtained by microwave synthesis in a few minutes, and they show high light scattering and larger surface area as well as improve the performance of dye-sensitized solar cells.

Energy-efficient, microwave-assisted hydro/solvothermal synthesis of hierarchical flowers and rice grain-like ZnO nanocrystals as photoanodes for high performance dye-sensitized solar cells

Hierarchical ZnO with different morphologies have been synthesized via rapid microwave-solvothermal method. Innovative ZnO nano-hybrid architecture photoanode based DSSCs showed remarkable enhancement in solar power conversion efficiency as high as 5.64%.